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Old 12-18-2019, 02:13 AM   #1
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Join Date: Jun 2009
Location: California
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Default S52 swap fuel pressure question / fuel trim

Hey all, my s52 is in and runs great but I had a quick question. I did not replace the fuel pressure regulator or the fuel pump (3bar vs 3.5). Should I? I would not worry about it except I am having a hard time passing CA smog due to high hydrocarbons only at idle.

It seems to me that if it were a low fuel pressure issue I would notice problems higher in rpm and under load in general. On the other hand I thought that it could also be caused by the computer opening the injectors longer to compensate for the lower overall pressure and the fuel trims not reacting fast enough when rpm drops to idle and dumping more fuel than needed causing the high HC issue. ( I might be WAY off on this and could use guidance! )

Thus far I have smoke tested the vacuum system, replaced all injectors, new o2's, new coils and plugs, and quite a few other things but no dice. The computer is clean, all monitors are ready with no faults and the car seems to run flawlessly.

One last bit of info, My long term fuel trims on bank 1 and 2 are +11.7 ( My assumption was this is also caused by the 3bar pressure regulator but again I may be off base here )

Sorry for the long read just trying to get info out there, any and all suggestions would be appreciated!
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Last edited by ilillund83; 12-18-2019 at 02:16 AM. Reason: Add Photo
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